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Throttle Body Bargains

We compare fifteen bargain throttle bodies...

By Michael Knowling

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Thinking about a bigger throttle body for your car? Not sure where to go or what to look for once you get there? Well, here's a story for you! We raid the wreckers to find the biggest and baddest throttle bodies that are available for relatively few dollars.

If you want maximum intake airflow, read on!

When is a Bigger Throttle Body Needed?

On some highly tuned engines it is possible for the throttle body to cause excessive intake airflow restriction. There is no rule of thumb to identify if your existing throttle body is restrictive - the only way to find out is through on-car testing. And, yes, it is a simple process!

All you need do is compare the intake system pressure before and after the throttle body while the engine is running at full power - the greater the pressure differential, the greater the restriction and so the need to upgrade the throttle body.

(Note that the rest of the intake manifold may also be restrictive at similar engine power.)

A Word On the Our Measurements

Our measurements of the fifteen throttle bodies have been made as accurately as possible. However, we were unable to remove every throttle body from the engines and this made some measurements (such as bolt pattern) very difficult. Please check all relevant information before handing over any money!

The Throttle Bodies...

Ford Falcon EA 3.9-litre

Click for larger image
The Ford Falcon EA throttle body is in abundant supply (in Australia, at least) and is one of the cheapest large units you can buy. With a 64mm throttle bore it delivers a 32.2cm2 cross-sectional area (ie ignoring the area of the fully open throttle blade), which is comfortably in the top 30 percent of the field. The overall length of the Ford throttle body is 98mm and four mounting bolts are arranged in 66mm square pattern. The inlet pipe has an oval shape that measures 75 x 86mm. Complete with throttle position sensor, this unit typically sells for just AUD$45 from All Panels and Parts Wreckers - a bargain.

Bore Diameter: 64mm

Bore Cross-Section (Ignoring Throttle Blade): 32.2cm2 (Rank 5th)

Overall Length: 98mm

Bolt Pattern: four bolts - 66mm square

Inlet Pipe (OD): 75 x 86mm oval

Holden VN Commodore 3.8-litre V6

Click for larger image
Due to demand, the Holden Commodore V6 throttle body is more expensive than the comparable Falcon unit. The VN V6 throttle bore is also slightly smaller than the EA Falcon's, with a cross-sectional area of 28.3cm2. Mounting this throttle is easy thanks to a simple 2-bolt mounting pattern and a round 80mm inlet pipe. At 102mm long, however, it does gobble more space than the Falcon unit. You'll pay AUD$65 at All Panels and Parts for a complete VN V6 unit.

Bore Diameter: 60mm

Bore Cross-Section (Ignoring Throttle Blade): 28.3cm2 (Rank equal 6th)

Overall Length: 102mm

Bolt Pattern: Two bolts - 102mm apart

Inlet Pipe (OD): 80mm round

Holden VN Commodore 5.0-litre V8

Click for larger image
The VN V8 Commodore is essentially the same as the V6 unit, but with one important difference - it has a 65mm bore, rather than 60mm. This increases its cross-sectional area from 28.3 to 33.2cm2. In all other respects - bolt pattern, overall length and inlet pipe diameter - it is identical to the V6 throttle body. Note that this is a popular bolt-on upgrade for V6 Commodores and, therefore, demand keeps the price up - a complete unit costs AUD$95 from All Panels and Parts.

Bore Diameter: 65mm

Bore Cross-Section (Ignoring Throttle Blade): 33.2cm2 (Rank 3rd)

Overall Length: 102mm

Bolt Pattern: Two bolts - 102mm apart

Inlet Pipe (OD): 80mm round

Holden VL Commodore 3.0-litre

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The VL 3.0-litre throttle body is another unit in abundant supply so, not surprisingly, you can pick one up from All Panels and Parts for AUD$65 (complete). The Nissan-developed RB30E breathes through a 55mm throttle bore, which is small compared to the other Aussie sixes and V8s. Its 23.8cm2 cross-sectional area is comparable with smaller capacity four-cylinder engines making around 100kW in factory guise. It is, however, quite compact making it suitable for installation in tight engine bays. Note that this throttle is reputedly a bolt-on upgrade for Nissan Pulsar/EXA turbos.

Bore Diameter: 55mm

Bore Cross-Section (Ignoring Throttle Blade): 23.8cm2 (Rank equal 13th)

Overall Length: 72mm

Bolt Pattern: Four bolts - 60mm square

Inlet Pipe (OD): 70mm round

Subaru Legacy/Liberty 2.0-litre Twin-Turbo

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With the highest power output of all the vehicles so far, you'd expect the 206kW Subaru Legacy TT to have a monster throttle body - not true! With a throttle bore of 60mm (28.3cm2) it is nothing special. It is, however, another compact unit that measures 62mm long overall. Note that this unit appears to be essentially the same as fitted to GC-series Impreza WRXs. Adelaide Japanese Dismantlers have these throttle bodies for AUD$85. (And, as you'll see, this price applies to most 'garden variety' throttles from this wrecker.)

Bore Diameter: 60mm

Bore Cross-Section (Ignoring Throttle Blade): 28.3cm2 (Rank equal 6th)

Overall Length: 62mm

Bolt Pattern: Four bolts - 65mm square

Inlet Pipe (OD): 70mm round

Subaru Legacy/Liberty 2.2-litre NA

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The naturally aspirated 2.2-litre Subaru flat-four uses the same basic throttle body design as the twin-turbo - no need for Liberty 2.2 owners to look at the Liberty TT/WRX for an upgrade throttle. Note that compared to the 2.0-litre twin-turbo, the 2.2-litre throttle is longer and has various different hose connections. You'll pay AUD$85 for one of these at Adelaide Japanese Dismantlers.

Bore Diameter: 60mm

Bore Cross-Section (Ignoring Throttle Blade): 28.3cm2 (Rank equal 6th)

Overall Length: 82mm

Bolt Pattern: Four bolts - 65mm square

Inlet Pipe (OD): 70mm round

Nissan S13 SR20DET (Red Rocker Cover)

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The Nissan S13 (Silvia and 180SX) 2.0-litre turbo engine is a common sight at Japanese import wreckers. But are their throttle bodies any good? Not really. The SR20DET throttle body is very similar to the Holden Commodore VL's except, most importantly, it has a larger 60mm bore diameter. Still, it's nothing special in any aspect - it's just another 60mm single-bore throttle. A SR20DET throttle body sells for AUD$85 at Adelaide Japanese Dismantlers.

Bore Diameter: 60mm

Bore Cross-Section (Ignoring Throttle Blade): 28.3cm2 (Rank equal 6th)

Overall Length: 70mm

Bolt Pattern: Four bolts - 60mm apart

Inlet Pipe (OD): 70mm round

Nissan R32 Skyline GTS-t RB20DET (Silver Rocker Cover)

Click for larger image
Perhaps not surprisingly, the Nissan Skyline R32's 2.0-litre turbocharged straight-six uses a very similar throttle to the SR20DET and the Holden VL 3.0-litre. The only obvious difference is its plumbing connections. Here's another non-event throttle body; expect to pay AUD$85 from Adelaide Japanese Dismantlers.

Bore Diameter: 60mm

Bore Cross-Section (Ignoring Throttle Blade): 28.3cm2 (Rank equal 6th)

Overall Length: 70mm

Bolt Pattern: Four bolts - 60mm square

Inlet Pipe (OD): 70mm round

Nissan/Infinity Q45 4.5-litre V8 (VH45DE)

Click for larger image
A-ha! Here's the monster of the group! Rated at more than 200kW, the VH45DE is Nissan's top-line 'VIP' engine that's a mechanical tour-de-force. You can quite literally fit your entire hand inside this throttle body - its 75mm bore is by f-a-r the biggest we've sampled. Ignoring the throttle blade, this unit gives a sensational cross-sectional area of 44.2cm2. We were unable to accurately measure its bolt pattern, but it is an offset square arrangement with less than 80mm from bolt centre to centre. You'll need a big feed pipe to connect to this bugger - its inlet pipe is a humungous 90mm in diameter! This is a brilliant throttle body if you can find one - Adelaide Japanese Dismantlers suggests you'll pay around AUD$150 for this rare beast.

Bore Diameter 75mm

Bore Cross-Section (Ignoring Throttle Blade): 44.2cm2 (Rank 1st)

Overall Length: 109mm

Bolt Pattern: Four bolts - offset square pattern

Inlet Pipe (OD): 90mm round

Toyota Supra/Soarer 3.0-litre Turbo (7M-GTE)

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A real grunter of an engine in its day (the late '80s) the Supra/Soarer's 3.0-litre turbo six is fitted with another run-of-the-mill throttle body. It has the common 60mm bore diameter (for a 28.3cm2 cross-sectional area) and is slightly longer than most of the other comparable units. These sell for AUD$85 from Adelaide Japanese Dismantlers.

Bore Diameter: 60mm

Bore Cross-Section (Ignoring Throttle Blade): 28.3cm2 (Rank equal 6th)

Overall Length: 95mm

Bolt Pattern: Four bolts - 70 x 55mm square

Inlet Pipe (OD): 70mm round

Toyota Soarer 2.5-litre Twin-Turbo (1JZ-GTE)

Click for larger image
The 1JZ-GTE (2.5-litre twin-turbo) has established a formidable reputation in tuning circles - it really is a gem of an engine. This ex-Soarer throttle body is equipped with a secondary throttle blade and motor, which is part of the vehicle's optional traction control system. This secondary throttle blade (which is located upstream of the normal throttle blade) adds to the length of the overall assembly - total length of this throttle body is a massive 165mm. Internally, though, it's the same 'ol 60mm diameter as the 7M-GTE and others. You'll pay AUD$85 for this throttle body from AJD. It might be worth it if you're looking at playing with traction control.

Bore Diameter: 60mm

Bore Cross-Section (Ignoring Throttle Blade): 28.3cm2 (Rank equal 6th)

Overall Length: 165mm

Bolt Pattern: Four bolts - 85 x 92mm square

Inlet Pipe (OD): 70mm round

Toyota/Lexus 4.0-litre V8 (1UZ-FE)

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And here's the second big banger of the group. The Toyota/Lexus 4.0-litre V8 boasts a throttle body bore of 70mm to give a cros-sectional area of 38.5cm2 - it is second only to the Nissan V8 throttle body. Like the 1JZ-GTE throttle, this unit is also fitted with a traction control butterfly that contributes to an overall length of 135mm. The four-bolt mounting pattern measures approximately 74mm square, except note that one of the bolts is further inset. At AUD$150 from AJD it's good buy, but go for the Nissan V8 throttle (at the same price) if one is available.

Bore Diameter: 70mm

Bore Cross-Section (Ignoring Throttle Blade): 38.5cm2 (Rank 2nd)

Overall Length: 135mm

Bolt Pattern: Four bolts - irregular (see text)

Inlet Pipe (OD): 80mm round

Mazda MX-5 BP 1.8-litre NA

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The Mazda MX-5 (Miata) is one of the most recognised sportscars of the modern era. With a 55mm throttle bore, it comes with a decent (for the power output) throttle as standard; note that it's the same size as the 3.0-litre Holden VL. This unit is more expensive than the Holden throttle, however - it costs AUD$85 from Adelaide Japanese Dismantlers.

Bore Diameter: 55mm

Bore Cross-Section (Ignoring Throttle Blade): 23.8cm2 (Rank equal 13th)

Overall Length: 62mm

Bolt Pattern: Four bolts - 60mm square

Inlet Pipe (OD): 65mm round

Mazda Familia GTX BP 1.8-litre Turbo

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Because the Mazda MX-5 (Miata) is such a commonly modified vehicle, we thought we'd see if the throttle from the turbocharged version of its BP-series engine is any bigger. It isn't. In fact, it appears identical in all of our measurements. Adelaide Japanese Dismantlers charge AUD$85 for this job.

Bore Diameter: 55mm

Bore Cross-Section (Ignoring Throttle Blade): 23.8cm2 (Rank equal 13th)

Overall Length: 62mm

Bolt Pattern: Four bolts - 60mm square

Inlet Pipe (OD): 65mm round

Mazda HC-Series 929 JE 3.0-litre V6

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And here's one outa left field. The late '80s HC Mazda 929 (hardtop and saloon) came with a sweet 3.0-litre V6 as standard fitment in the Australian market. Interestingly, its throttle body contains a pair of 45mm bores with twin butterflies that open simultaneously. It's quite a large unit and it does need an unusual bolt pattern but it's certainly an interesting one to keep in mind. These sell for AUD$125 from Adelaide Japanese Dismantlers.

Bore Diameters: Twin 45mm

Total Bore Cross-Section (Ignoring Throttle Blades): 31.8cm2 (Rank 4th)

Overall Length: 92mm

Bolt Pattern: Four bolts - 113 x 65mm square

Inlet Pipe (OD): 115 x 75mm oval

The Results at a Glance...

As you can see, our selection of throttle bodies offer a cross-sectional area ranging from 23.8cm2 to a maximum of 44.2cm2. In other words, the largest throttle body is 86 percent bigger than the smallest!

If you're after all-out performance you can't go past the Nissan and Toyota V8 throttle bodies (at 44.2 and 38.5cm2 respectively). The Nissan unit is the clear winner, though, since it offers the greatest flow potential at the same price as the slightly smaller Toyota V8 throttle. Its AUD$150 price tag is an absolute bargain if you compare it to anything from the aftermarket.

For sheer bang-for-buck, the Ford EA throttle is the stand-out - it offers the 5th largest cross sectional area along with a price tag of just AUD$45 (the cheapest of all!). Another cost-effective unit is the Holden VN V8, which gives 3rd greatest cross sectional area at a price of AUD$95.

The above data shows that OE throttles rarely exceed 60mm diameter except in naturally aspirated engines rated at about 150kW or more. Keep this in mind if you decide to go searching for other throttle bodies - powerful atmo engines usually have the biggest and baddest throttles!

Considerations for a Throttle Body Conversion

If you decide to go ahead with a throttle body conversion there are a few important considerations. Obviously, you need to find a way to mount the new throttle body to the engine but you must also ensure that it is compatible in terms of sensors and plumbing. For example, the TPS (Throttle Position Sensor) must have the same characteristics as your existing unit in order for the engine management system to cope. If it doesn't have the same TPS output, you will need to look at adapting your original TPS to suit - and this is not possible in all cases. You should also check the compatibility of throttle body coolant connections, idle air bypass passages, EGR and all other plumbing.

Don't jump in without checking out these areas first!

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